1. Field of the Invention
The present invention relates generally to a sensor for measuring patient physiological characteristics. More particularly, embodiments of the present invention relate to a sensor that measures oxygen content in a patient's blood and that limits misuse of the sensor, such as tampering with or remanufacturing of the sensor.
2. Description of the Related Art
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Pulse oximetry may be defined as a non-invasive technique that facilitates monitoring of a patient's blood characteristics. For example, pulse oximetry may be used to measure blood oxygen saturation of hemoglobin in a patient's arterial blood and/or the patient's heart rate. Specifically, blood characteristic measurements may be acquired using a non-invasive sensor that passes light through a portion of a patient's blood perfused tissue and that photoelectrically senses the absorption and scattering of light through the blood perfused tissue. A typical signal resulting from the sensed light may be referred to as a plethysmographic waveform. Once acquired, this measurement of the absorbed and scattered light may be used with various algorithms to estimate an amount of blood constituent in the tissue, as well as other physiologic characteristics.
Conventional pulse oximeter sensors typically include emitters (e.g., a red emitter and an infrared emitter) configured to emit light waves and a photodiode detector that is arranged to detect the emitted light waves. Such sensors are typically configured to attach to a patient's finger, foot, forehead, or earlobe to facilitate measurement of blood characteristics in the associated tissue. For example, a typical oximeter sensor may be adapted to project light from the emitters through the outer tissue of a finger and into the blood vessels and capillaries inside. Such a sensor typically includes a detector that is arranged to detect the emitted light as it emerges from the outer tissue of the finger. The detector generates a signal based on the detected light and provides the signal to an oximeter, which determines blood oxygen saturation based on the signal.
Some conventional sensors also include an information element that stores information that can be read by an attached device to facilitate proper blood characteristic measurement. For example, a pulse oximeter sensor may include a memory or a resistor that can be read by an oximeter. The information stored on the information element (e.g., resistor, memory) may include parameters about the sensor. For example, the information may indicate sensor type (e.g., neonatal, pediatric, adult), the wavelengths of light produced by the emitters, and so forth. This information may be utilized in algorithms for determining values for the blood characteristic. Further, the information element may be utilized for security and quality control purposes. For example, the information element may ensure proper operation by preventing the sensor from functioning with improperly configured or unauthorized devices.
Improper remanufacturing of a sensor or tampering with the sensor can impact the quality and reliability of the sensor. For example, improper remanufacturing of a sensor may eliminate the quality assurance function of the information element or cause malfunctions by coupling incompatible sensor components together. In a specific example, an information element for a neonatal oximeter sensor may be improperly incorporated into an adult oximeter sensor during remanufacture. Such remanufacturing can cause improper operation and incorrect measurement of physiological characteristics.